One of the golden rules of smart money management is to set up a budget and stick to it, right? Well, flying in the face of that common wisdom is this new study that shows sometimes budgeting backfires.

In the experiments, conducted by Brigham Young University and Emory University marketing professors, consumers spent up to 50 percent more when they went shopping with a price in mind compared to those who didn't have a budget for that item. Setting a target price for an item can actually prompt us to spend more than we intend when we get to the store, because once we "screen our choices based on price," the researchers say, "we essentially ignore price after that and focus on quality" when we get to the store. "And better quality products usually cost more."

For example, in one of the experiments, the researchers asked a group of consumers how much they would be willing to spend on a new TV. Those consumers were then given the option of choosing a TV $18 above their target price and a lower-quality one $18 below. About 55 percent of them chose the higher-priced option that was above their target price range. But among a set of consumers who were given the same options WITHOUT being asked how much they would be willing to spend, only 31 percent chose the higher-priced option. Those who set a maximum price first also rated the difference in quality between the choices as much greater than those who didn't.

Setting budgets for "aggreggate" things—like groceries in general or all of your finances is still wise, but for individual, specific purchases, the research suggests that you start first by thinking about quality and features before thinking about price, to protect yourself from this effect. Also, force yourself to reconsider the price, now that you know about this effect.